copysign(), copysignf()

Copy the sign bit from one number to another

Synopsis:

#include <math.h>

double copysign ( double x,
                  double y);

float copysignf ( float x,
                  float y );

Arguments:

x
The number to use the magnitude of.
y
The number to use the sign of.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

The copysign() and copysignf() functions return the magnitude of x and the sign bit of y.

If x is NAN, the function produces NAN with the sign of y.

Returns:

The magnitude of x and the sign bit of y.

Examples:

#include <stdio.h>
#include <errno.h>
#include <inttypes.h>
#include <math.h>
#include <fpstatus.h>

int main(int argc, char** argv) 
{
   double a, b, c;

   a = 27.0;
   b = -5;
   c = copysign(a, b);
   printf("The magnitude of %f and sign of %f gives %f\n",
          a, b, c);

   return(0);
}

produces the output:

The magnitude of 27.000000 and sign of -5.000000 gives -27.000000

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes

Last modified: 2013-12-23

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